Heat exchanger



March 28, 1967 J. KARMAZIN 3,311,165

HEAT EXCHANGER Filed March 9, 1965 INVENTOR. JZZW K477714112? United States Patent This invention relates to heat exchangers, and particularly to a heat exchanger made from a plurality of nested tube sections having heat conductive fins.

It is an object of the present invention to provide a heat exchanger having increased heat dissipating ability.

It is another object of the present invention to provide a. heat exchanger which possesses substantial structural strength, which is of durable construction, which may be inexpensively fabricated, and which possesses a relatively high capacity for the volume of space which it occupies.

These and other objects of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a fragmentary sectional view of a sheet of metal having projections formed therein and which is used in manufacturing the heat exchanger of the present invention;

FIG. 2 is a fragmentary bottom plan view of a heat exchanger made from a plurality of sheets of the type shown in FIG. 1;

FIG. 3 is a sectional view of the structure illustrated in FIG. 1 taken along the line 33 thereof; and

FIG. 4 is a view of structure similarly illustrated in FIG. 1, showing a modified form of the present invention.

Referring now to the drawings, the heat exchanger of the present invention is made from a plurality of diestamped sheets 6 of suitable metallic material. These sheets 6 are each provided with tapered tubular projections 8 integrally formed therein by a progressive die mechanism (not shown). The tubular projections 8 define completely unobstructed openings 10 at the ends thereof adjacent a flat or fin portion 12 of the sheet 6. Each tubular projection 8 has a mouth or terminus 14 which is of circular cross section and which has a transverse strip of material 16 extending diametrically thereacross. The terminus 14 is open on the sides of the strip 16. A pair of vanes 18 are connected to the opposite side edges 28 of the strip 16. The portions of the vanes 18 adjacent the strip lextend in a direction parallel to the axis of the tube sections 8, but terminal portions 22 of the vanes are inclined in a radially outward diverging direction.

As illustrated in FIG. 3 the heat exchanger is formed from a plurality of identical sheets 6 which are stacked together so that the tubular projections 8 of one sheet nest into the projections 8 of a next adjacent sheet. In the embodiment of the invention illustrated herein, the sheets 6 have just one row of tubular projections 8. It will be appreciated, however, that each sheet 6 may be formed with a plurality of such rows. It will be seen that the outside diameter of each tube section terminus 14 is smaller than the tube openings 10. By this means each terminus 14 will fit into the opening 10 of the next adjacent tubular projection S. The nested tubular projections 8, therefore, cooperate to define conduits 24, with the vanes 18 being spaced along the length of such conduits.

The various conduits 24 are ordinarily interconnected by suitable return members or headers (not shown) at the opposite ends of the heat exchanger to define a flow path. Preferably, however, fluid is caused to flow down each of the conduits 24 in the same direction that the vanes 18 extend from the strip 16. Under such circumstances, fluid striking the radially outer surfaces of vane portions 22 will be directed radially outwardly against the inside wall of the conduits 24. This creates a turbu- 3,311,165 Patented Mar. 28, 1967 "Ice lence within the conduits 24 and tends to break up any film of material tending to cling to the inside walls of the conduits 24. This has been found to produce a marked increase in the heat capacity of the unit as compared to a heat exchanger core in which the vanes 18 extend entirely in a direction completely parallel to the axis of the conduits 24.

In forming the conduits 24, the nested tubular projections 8 are secured together by means of brazing. This is accomplished by inserting lengths of copper or other brazing material and flux into the conduits 24 and then placing -the assembled heat exchanger in a brazing furnace. The brazing material will flow between the interfitting tubular project ons 8 by capillary action to seal the joints between the tubular projections and mechanically bond the sheets 6 together.

FIG. 4 illustrates a modified form of the present invention utilizing a sheet 26 having a plurality of tapered tube sections 28 which are integrally formed with fins 35 consisting of the unindented portion of the sheet 26. The tube sections 28 have terminal end portions 30 provided with narrow cross strips 32. The strips 32 have arcuately shaped vanes 34 projecting from their opposite sides which extend in diverging axially and radially inclined directions over their entire lengths. The sheet 26 wlil be seen to differ from the sheet 6 solely by virtue of the shape of the vanes 34, the vanes 34 being of planar configuration whereas the vanes 18 are provided with terminal portions 22 bent at an angle to the remaining portion of the vane. The vanes 34 perform a function similar to the vanes 18 in deflecting fluid flowing from the large end to the small end of the tube sections 28 in a radially outward direction against the Wall of the next adjacent tube section 28, thereby increasing the turbulence of the fluid within the heat exchanger, breaking up any surface film tending to cling to the walls of the tube sections and changing the fluid in contact with the walls of the tube sections 28. It will be seen that the vanes 34 are formed integrally with the strips 32 and tube sections 28.

In one embodiment of the present invention constructed essentially as shown in FIG. 2, the tubular projections 8 each had a terminus 14 which was 3 inch or .344 inch in diameter. The transverse strip of material 16 was .108 inch in width and the vane portions 22 spanned a width of about .178 inch in a direction perpendicular to the strip 16. This heat exchanger was found to give significantly higher heat transfer results as compared to a heat exchanger which did not incorporate the vanes 18. It is believed that vanes spanning a width (in a direction perpendicular to the length of the strip 16) of at least 40% of the adjacent tube width, or vanes having an increase in spanned width of at least 40% over the width of the transverse material 16 from which they emanate, will produce highly desirable results. In the above specific example the increase in width of the vanes 22 over the strip 16 was about 65%.

It has been found that the presence of the vanes 18 or 34 tends to obstruct the flow of fluid somewhat and reduce fluid pressure. However, it is possible to keep the total pressure drop within acceptable limits by suitable interconnection of the conduits 24 at their ends to reduce the number of passes the fluid makes in flowing through the heat exchanger. Controlling the number of passes is simply a question of header design and is Within the skill of those familiar with the heat exchanger art. By this means it has been found possible to produce a heat exchanger in accordance with the present invention which has a lesser pressure drop than other commercially available heat exchangers of comparable capacity.

While the preferred embodiments of the invention illustrated herein are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible of modification, variation, and change without departing from the fair meaning or scope of the subjoined claims.

What is claimed is:

1. A heat exchanger including a plurality of integral tube and fin members having their tubes arranged in nested relationship, at least some of said tubes having a terminal portion provided with a transverse strip of material and openings at the sides of said strip, and a pair of vanes connected to said strips and extending therefrom in diverging directions inclined to the axis of the tube sections so as to direct fluid flowing along said tubes in a radially outward direction aganst the walls of the adjacent tubes, the vanes of said tubes being spaced from the vanes of the tubes adjacent thereto to create turbulence in the fluid flowing through said tubes.

2. A heat exchanger including a plurality of integral tube and fin members having their tubes arranged in nested relationship, at least some of said tubes having a terminal portion provided with a transverse strip of material and openings at the sides of said strip, and a pair of vanes connected to said strips, at least a portion of said vanes extending in a radially outwardly and axially inclined direction so as to direct fluid flowing through the adjacent openingsradially outwardly against the walls of the adjacent tubes, the vanes of each of said tubes being spaced from the vanes of the tubes adjacent thereto to create turbulence in the fluid flowing through said tubes.

3. A heat exchanger including a plurality of integral- 4 strips of material are connected, the vanes of each of said tubes being spaced apart from the vanes of the tubes adjacent thereto to create turbulence in the fluid flowing through said tubes.

4. A heat exchanger including a plurality of integral tube and fin members having their tubes arranged in nested relationship, at least some of said tubes having terminal portions provided with transverse strips of material and openings at the sides of said strips, and pairs of diverging vanes connected to the opposite sides of said strips and extending radially and axially therefrom, each pair of said vanes having a growth in spanned width in a direction perpendicular to the length of their associated strip equal to at least of the width of said strip, the vanes of each of said tubes being axially spaced from the vanes of the tubes at opposite ends thereof to create turbulence in the fluid flowing through said tubes.

5. A heat exchanger including a plurality of integral tube and fin members having their tubes arranged in nested relationship, at least some of said tubes having terminal portions provided with transverse strips of material and openings at the sides of said strips, and pairs of diverging vanes connected to the opposite sides of said strips and extending radially and axially therefrom, each pair of said vanes having a growth in spanned width in a direction perpendicular to the length of their associated.

strip equal to about of the width of said strip, the vanes of each of said tubes being axially spaced from the vanes of the tubes at opposite ends thereof to create turbulence in the fluid flowing through said tubes.

References Cited by the Examiner UNITED STATES PATENTS 1,940,804 12/1933 Karmazin 15l ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner, 

1. A HEAT EXCHANGER INCLUDING A PLURALITY OF INTEGRAL TUBE AND FIN MEMBERS HAVING THEIR TUBES ARRANGED IN NESTED RELATIONSHIP, AT LEAST SOME OF SAID TUBES HAVING A TERMINAL PORTION PROVIDED WITH A TRANSVERSE STRIP OF MATERIAL AND OPENINGS AT THE SIDES OF SAID STRIP, AND A PAIR OF VANES CONNECTED TO SAID STRIPS AND EXTENDING THEREFROM IN DIVERGING DIRECTIONS INCLINED TO THE AXIS OF THE TUBE SECTIONS SO AS TO DIRECT FLUID FLOWING ALONG SAID TUBES IN A RADIALLY OUTWARD DIRECTION AGANST THE WALLS OF THE ADJACENT TUBES, THE VANES OF SAID TUBES BEING SPACED FROM THE VANES OF THE TUBES ADJACENT THERETO TO CREATE TURBULENCE IN THE FLUID FLOWING THROUGH SAID TUBES. 